Non-invasive, transdermal sampling of body fluids has long been a goal of medical research. Prior art attempts to achieve this goal are described in, for instance U.S. Pat. No. 6,887,202 issued on May 3, 2005 to Currie et al. entitled “Systems and Methods for Monitoring Health and Delivering Drugs Transdermally” the contents of which are hereby incorporated by reference.
The prior attempts at transdermal sampling have typically been characterized by making relatively large holes in the outermost layer of the epidermis, namely the stratum corneum which is effectively the surface of the skin and is composed mainly of dead cells that lack nuclei. The holes are typically made by heat or laser ablation or puncturing with fine needles and reach through to underlying, viable epidermis. Interstitial fluid from the viable epidermis or fluid from the extremity of the vascular system is then typically either sucked up, or squeezed out, from beneath the skin into the transdermal device where it is analyzed spectroscopically using systems of micro-fabricated channels and light guides.
Such systems have many drawbacks, including the fact that the size of the holes is typically of the order of tens of microns which is sufficient to cause local irritation. This often results in inflammation, which typically prevents the channels typically from being maintained open for longer than a few hours to a few days.
Furthermore, micro-fabrication of complex systems typically requires the use of silicon substrates, which are relatively inflexible, thereby making close surface contact difficult and resulting in lateral motion between the transdermal detector and the holes through the stratum corneum. Because of the size of the transdermal holes, typically tens of microns in diameter, even a small amount of lateral motion can render such a device inoperative.
It is desirable to provide a configurable flexible personal health monitoring and delivery system that may be configured to be used in a much wider range of applications. It is also desirable to provide a sampling device that may be used in invasive, minimally invasive, and non-invasive procedures involving transdermal and non-transdermal sampling.